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authorSowmini Varadhan <sowmini.varadhan@oracle.com>2018-01-04 17:53:00 +0300
committerDavid S. Miller <davem@davemloft.net>2018-01-05 21:39:18 +0300
commit3db6e0d172c94bd9953a1347c55ffb64b1d2e74f (patch)
tree67f61aa4784da3fba56aa43e3626d3f3b6562c78 /net/rds/cong.c
parentc90ecbfaf50d2d7db25c531d9169be7e47435f3f (diff)
downloadlinux-3db6e0d172c94bd9953a1347c55ffb64b1d2e74f.tar.xz
rds: use RCU to synchronize work-enqueue with connection teardown
rds_sendmsg() can enqueue work on cp_send_w from process context, but it should not enqueue this work if connection teardown has commenced (else we risk enquing work after rds_conn_path_destroy() has assumed that all work has been cancelled/flushed). Similarly some other functions like rds_cong_queue_updates and rds_tcp_data_ready are called in softirq context, and may end up enqueuing work on rds_wq after rds_conn_path_destroy() has assumed that all workqs are quiesced. Check the RDS_DESTROY_PENDING bit and use rcu synchronization to avoid all these races. Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/cong.c')
-rw-r--r--net/rds/cong.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/net/rds/cong.c b/net/rds/cong.c
index 8398fee7c866..8d19fd25dce3 100644
--- a/net/rds/cong.c
+++ b/net/rds/cong.c
@@ -219,7 +219,11 @@ void rds_cong_queue_updates(struct rds_cong_map *map)
spin_lock_irqsave(&rds_cong_lock, flags);
list_for_each_entry(conn, &map->m_conn_list, c_map_item) {
- if (!test_and_set_bit(0, &conn->c_map_queued)) {
+ struct rds_conn_path *cp = &conn->c_path[0];
+
+ rcu_read_lock();
+ if (!test_and_set_bit(0, &conn->c_map_queued) &&
+ !test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
rds_stats_inc(s_cong_update_queued);
/* We cannot inline the call to rds_send_xmit() here
* for two reasons (both pertaining to a TCP transport):
@@ -235,9 +239,9 @@ void rds_cong_queue_updates(struct rds_cong_map *map)
* therefore trigger warnings.
* Defer the xmit to rds_send_worker() instead.
*/
- queue_delayed_work(rds_wq,
- &conn->c_path[0].cp_send_w, 0);
+ queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
}
+ rcu_read_unlock();
}
spin_unlock_irqrestore(&rds_cong_lock, flags);